The invention relates to hydraulic antivibration supports.
More precisely, the invention relates to a hydraulic antivibration support adapted to be interposed between first and second rigid elements undergoing a relative vibratory motion at least vertically and parallel to a substantially horizontal first axis, for supporting one of the first and second rigid elements and for damping said vibratory motions along said first axis.
Such hydraulic antivibration supports are known in the art.
For instance, as shown in FIG. 1 of the drawings, one known antivibration support 1 of this type, which is designed to connect a first rigid element 2 such as a vehicle body to a second rigid element 3 such as a vehicle engine, includes a supporting device 4 having first and second connection members 5, 6 which are respectively fixed to the first and second rigid elements 2, 3.
The first and second connection members 5, 6 are connected together by an elastomer body 7 having two thick arms 7a, 7b able to withstand part of the weight of the second rigid element 3.
The elastomer body 7 enables relative movements between the first and second rigid elements 2, 3 parallel to first and second horizontal axes X, Y and parallel to a vertical axis Z.
Further, in order to damp the relative movements between the first and second rigid elements 2, 3 parallel to the first horizontal axis X, the antivibration support 1 further includes a damping device 8, which can be seen in more details in FIG. 2.
The damping device 8 includes a rigid ring of metal 9 which may be fixed for instance to the first rigid element 2 through a bracket 10 and which may be fixed by crimping to a rigid cover 11, itself fixed to a stud 12. The stud 12 may be itself fixed to the first rigid element 2 and possibly to a U shaped guide member 13 (FIG. 1).
Further, the damping device 8 includes a rigid plate 14 (FIG. 2) which is extended, opposite to the cover 11, by a rod 15 parallel to axis X, said rod being slidingly mounted in guide 13 and connected, for instance through an antivibration sleeve 15a, to a bracket 3a which is fixed to the second rigid element 3.
The plate is overmolded by an elastomer membrane 16 which is also overmolded on the ring 9. An other elastomer membrane 16a is fixed to the ring 9 inside the cover 11, and the inner space between the two membranes 16, 16a is separated into two chambers 17, 18 by a rigid partition 19 including a decoupling membrane 20 and a throttled channel 21 in communication with the two chambers 17, 18, said chambers 17, 18 and said channel 21 being filled with a liquid.
This known antivibration support has the drawbacks of being expensive and bulky.
A second known antivibration device 30 of the type in question is shown in FIG. 3.
This second antivibration device of the prior art includes a first rigid strength member 31 which is fixed to an outer rigid tube 32 and which is designed to be fixed to the first rigid element 2 as described above.
The antivibration support 30 also includes a second rigid strength member 33 which may extend longitudinally parallel to axis Y and which is designed to be fixed to the second rigid element 3 as described above.
An elastomer body 34 is fitted inside the tube 32 and includes two thick arms 35 converging upward toward the second strength member 33 so as to be able to withstand at least part of the weight of the second rigid element 3. The elastomer body further includes two deformable walls 36 delimiting two hydraulic chambers 37, 38 with the tube 32. These hydraulic chambers 37, 38 are filled with liquid and communicate together through a throttled channel 39.
Thus, when the first and second rigid elements 2, 3 undergo relative horizontal movements parallel to axis X, the second rigid strength member 33 presses alternately the deformable walls 36 of the two chambers 37, 38, thus provoking transfers of liquid between the two chambers, which damps said horizontal movements.
The antivibration support of FIG. 3 has also the drawbacks of being expensive and rather bulky, specially in the vertical direction.
One objective of the present invention is to remedy these drawbacks, for a cost as limited as possible.
To this end, according to the invention, a hydraulic antivibration apparatus of the type in question includes:
a first rigid connection device adapted to be fixed to the first rigid element, said first connection device including a base and a substantially vertical pin extending from the base,
a second rigid connection device adapted to be fixed to the second rigid element, said second connection device including a rigid tube having a substantially vertical central axis,
a first elastomer body connecting the base of the first connection device to the second connection device, said first elastomer body being adapted for supporting one of the first and second rigid elements,
a second elastomer body which is disposed inside said rigid tube and which defines therewith at least two deformable hydraulic chambers filled with liquid and connected together by a throttled channel, said second elastomer body including at least two deformable walls which partially define the hydraulic chambers and which are substantially aligned parallel to said first axis so as to be deformed by the pin during relative movements of the first and second connection devices parallel to said first axis, said pin extending in a substantially vertical free passage defined between said deformable walls, and said second elastomer body being free to move vertically relative to said pin without substantially being deformed.
Thanks to these dispositions, the antivibration support is compact and, since the supporting and damping functions are carried out by two separate elastomer bodies, the shapes and mounting of these bodies is rather simple, so that the support can be manufactured at a reasonable cost.
In various embodiments of the invention, one may possibly have recourse in addition to one and/or other of the following arrangements:
each of said deformable walls includes an inner portion which is in close proximity to the pin, and which is free to move vertically relative to said pin;
said pin is disposed in said free passage with a larger play parallel to a substantially horizontal second axis than parallel to the first axis, said second axis being perpendicular to the first axis;
the second elastomer body includes two lateral elastomer bosses which are adapted to be abutted by the pin parallel to the second axis for limiting relative movements of the first and second connection devices parallel to said second axis;
the second connection device further includes a first rigid strength member on which the first elastomer body is molded, and a second rigid strength member which is fixed to said tube;
said tube is fitted in the second strength member of the second connection device;
the first strength member of the second connection device includes a central hole delimited by a horizontal annular flange which is in vertical abutment with said rigid tube in the direction of the base, and said first strength member of the second connection device further includes a tubular portion of substantially vertical axis surrounding said flange, said rigid tube being fitted in said tubular portion;
said first elastomer body includes a lower elastomer boss adapted to cooperate with said flange to limit a relative vertical movement of the first and second connection devices toward one another;
the second elastomer body includes at least a vertical boss which protrudes opposite of the base and which is adapted to cooperate by abutment with a transverse rigid member fixed to the pin, for limiting vertical relative movement of the first and second connection devices apart from one another.